Washington, which has adopted a hardline Iran policy under Donald Trump, is seeking to extend a UN Security Council ban that keeps Iran from importing technology and missiles used in both conventional and nuclear weapon delivery systems.

The United States has threatened to force a unilateral “snapback” of all UN sanctions against Iran if the Security Council does not extend its arms embargo.

Washington will ensure “one way or another” that the embargo remains in place, Brian Hook, the US special envoy for Iran and senior policy adviser to Secretary of State Mike Pompeo, wrote in a Wall Street Journal column published on Wednedsay.

Hook added that the US had drafted a Security Council resolution and “will press ahead with diplomacy and build support.”

A 13-year-old United Nations-mandated arms embargo on Iran is supposed to expire on 18 October 2020. Most other UN sanctions against the Islamic Republic were lifted in 2016, after the hard-fought nuclear deal came into force.

The United States withdrew from the agreement in May 2018 after lobbying by Israel, claiming that it was flawed and worked to Iran's advantage, despite objections from the rest of the signatories – Russia, China, the UK, France, and Germany. The US unilaterally re-imposed strangling sanctions on Iran's oil exports and financial sector and is seeking to prolong the arms embargo indefinitely.

When it comes to UN sanctions, the deal contains “snapback” provisions which will renew the penalties if Iran does not comply with its nuclear commitments. Iran started scaling back its compliance with the deal in May 2019 to pressure European countries to shield it from US sanctions, and announced a final rollback this January. However, international experts monitoring its nuclear programme are still allowed to visit, and Iran has pledged to restore all of its commitments if the US acts in kind.

Although the US has left the agreement, the Security Council has never amended the resolution that endorsed it to remove the US from the deal. The US State Department reportedly wants to use that legal charade to justify the position that it technically remains a participant to be able to press ahead with the embargo.

Iran has already objected to an embargo extension, and so has Russia. “I do not see any reason why an arms embargo should be imposed on Iran,” Russia's UN ambassador Vasily Nebenzya said this week. “You know, in order to be able to use the instruments provided by the JCPOA, you first have to be a participant of the JCPOA. The US has not been an effective participant of the JCPOA for two years now.”